Process and apparatus for reduction of microorganisms in a conductive medium using low voltage pulsed electrical energy

ABSTRACT

A process and apparatus are provided for reducing microorganisms in a conductive medium using a low voltage pulsed electrical energy.

[0001] This application is a continuation-in-part of application Ser.No. 09/557,963 filed Apr. 25, 2000.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] A process and apparatus is provided for the reduction ofmicroorganisms in a conductive medium using low voltage pulsedelectrical energy.

[0004] 2. Description of Related Art

[0005] Reduction of microorganisms in a medium using electricity hasbeen studied for many decades. Most early efforts focused on thereduction of microorganisms in a medium by passage of a high voltageelectric current through the medium to generate heat, thereby killingthe microorganisms in the medium by pasteurization. The conductivemedium was often a pumpable food or beverage, such as milk or water.

[0006] Later efforts focused on the reduction of the microorganisms byso-called “nonthermal” pasteurization methods. These methods involveapplication of a high voltage electric field to the medium in shortpulses. The high voltage electric field generates an applied energy of150 joules/ml or greater and causes death of the microorganisms byelectroporation or lysis of the microbial cell membrane. The shortnessof the pulse duration attempted to minimize heating of the medium.However, these methods suffer from numerous disadvantages, especiallywhen applied to pumpable foods and beverages. For example, the highvoltage electric field when applied to pumpable foods and beverages cancause structural alterations in the food or beverage, adverselyeffecting the taste and texture of the food or beverage. In addition,such high applied energies are believed to cause the formation of freeradicals in foods and beverages, which compounds are considered to causeor promote cancer. Further, the equipment necessary to generate suchhigh applied energies requires an electrical energy on the order of 100kV/cm. Furthermore, such methods do not appear to kill all types ofmicroorganisms, such as molds and yeast.

[0007] Experiments have been conducted in the prior art using lowvoltage electric fields. However, these electrical energy applicationswere considered to be unsatisfactory because they were not deemed tocause irreparable damage to the microorganisms.

[0008] As examples of the prior art, reference is made to the followingU.S. patents, whose teachings are incorporated by reference: U.S. Pat.No. 4,917,785; U.S. Pat. No. 4,957,606; U.S. Pat. No. 5,026,484; U.S.Pat. No. 5,037,524; U.S. Pat. No. 5,464,513; U.S. Pat. No. 5,514,391;U.S. Pat. No. 5,630,915; U.S. Pat. No. 5,766,447; and the followingpublications: Bai-Lin Qin et al., “Inactivating Microorganisms Using aPulsed Electric Field Continuous Treatment System”, IEEE Transactions onIndustry Applications, Vol. 34, No. 1, January/February 1998; Karl H.Schoenbach et al., “The Effect of Pulsed Electrical Fields On BiologicalCells”, paper presented at EPRI/Army PEF Workshop II, Chicago, Ill. onOct. 10-11, 1997; K. H. Schoenbach et al., “Effect of Pulsed ElectricFields on Micro-organisms: Experiments and Applications, paper presentedat EPRI/Army PEF Workshop II, Chicago, Ill. on Oct. 10-11, 1997; andKarl H. Schoenbach et al., “The Effect of Pulsed Electric Fields onBiological Cells: Experiments and Applications”, IEEE Transactions onPlasma Science, Vol. 25, No. 2, April 1997.

SUMMARY OF THE INVENTION

[0009] The process of this invention improves on the prior art byproviding a method of microbial reduction in a conductive medium whichaffects the target microorganism(s) without causing detrimental effectsto the medium. The term “reduction” is used in its conventional sense inthe art to mean that the method results in mortality to some or alltarget organisms. In other words, after treatment with the method ofthis invention, the treated medium contains a substantially decreasednumber of viable microorganisms. Applications include conductive mediumssuch as pumpable foods, beverages, processing fluid streams, blood,water, and eco-system waters, as well as conductive solids and solidssuspended in liquids or gases to include air, which mediums aremicrobiologically infected and capable of causing harm to thoseconsuming or coming in contact with the infected medium. The term“pumpable foods” means any food which is capable of being pumped orconveyed through pipes or conduits, including solid food items conveyedin a conductive aqueous solution. Examples of solid food items in thislater category are fruits and vegetables. Conductive solids means anysolid item capable of being pumped or conveyed through pipes, conduitsor channels. Examples in this category are powderized materials.Suspended solids means any solid suspended in a liquid or gas. Examplesin this category are food items in carrier liquids or volatile suspendedsolids in a wastewater facility.

[0010] The method of this invention involves the application of lowvoltage pulsed electrical energy having defined voltage, frequency andpulse waveform characteristics to the target microorganisms in themedium. By the term “low voltage pulsed electrical energy”, it is meantthat the combination of energy, frequency and pulse waveform applied tothe microorganisms must be such that no free radicals are formed, noionizing radiation is created, and no osmotic shock waves are formed.The term “low energy pulses” which is used herein by the inventor hasthe same meaning. It is surprising that the low energy pulses result incell mortality, since the energy pulses are too low to causeelectroporation or lysis of the microbial cell membrane. The specificmechanism by which the method of this invention causes mortality of themicroorganisms is not clearly understood. One theory is that the lowenergy pulses of specific voltage, frequency and pulse waveform cause adisruption in an essential component of the intricate cellular machineryof the microorganism, such as a disruption of the metabolic and/orrespiration cycles of the target microorganism. Regardless of exactlyhow the method of this invention operates to cause mortality tomicroorganisms, the inventor has demonstrated through extensiveexperimental tests which are summarized herein that the method issurprisingly effective. Accordingly, when the method is applied with theproper know-how described herein, the ordinary skilled person canachieve substantial reductions in target organisms in a conductivemedium by application of low energy pulses which do not have detrimentaleffects on the medium. As an example of detrimental effects to a medium,there is mentioned the occurrence of organo-leptic changes to a mediumwhich is a pumpable food or beverage.

[0011] The effective voltage, pulse frequency and waveformcharacteristics of each target organism are unique, and therefore theprocess requires the ability to vary the frequency of energy delivery aswell as to vary the voltage applied, with a limitation being such thatno combination of applied voltage, pulse frequency and waveform appliedis capable of creating structural membrane alterations of the targetorganisms, e.g., electroporation or lysation of the target organism.Additionally, the combination of energy, pulse frequency and waveformapplied must be such that no free radicals are formed, no ionizingradiation is created, nor osmotic shock waves formed. Further, there issubstantially no temperature increase or pressure increase.

[0012] This process improves on the prior art of disinfection byaffecting only the target organism, not the medium. This is accomplishedby the controlled release of pulsed energy into a treatment space, suchas a conduit or chamber. The process and apparatus may provide formultiple treatment spaces in continuous parallel or series flow paths.The process and apparatus may be installed in a continuous flowproduction line or in a container, such as a batch storage tank.

[0013] The combination of voltage, pulse frequency and pulse waveformare refined such that the energy applied to the target organism disruptsthe respiration and/or metabolic codes of the target organism therebykilling the organism. As metabolic and respiration codes are requiredfor living organisms to function, disruption of the codes cause theelimination of the reproductive cycle and death. Surprisingly, theprocess of the present invention is even capable of killingmicroorganisms, such as molds and yeast, which are not effected by highvoltage electric field methods.

[0014] As the voltage, pulse frequency and pulse waveform of the pulsedelectrical energy are control parameters, it is preferable toincorporate monitoring with process control into the overall processdesign to accomplish commercial viability by insuring processconsistency, operator safety and documentation of treatment.

[0015] Preferably, the parameters to be monitored and controlled whichare incorporated into the process design are flow rate of the medium,conductivity of the medium, pH of the medium, pressure of the medium,temperature of the medium, voltage potential between the cathode andanode electrodes of the pulser, current generated by the electrodes intothe medium, frequency of the electric pulse, the shape and amplitude ofthe electric pulse which define the pulse waveform, and the appliedenergy which is exerted on the microorganisms in the particular medium.

[0016] It is specifically noted the process and apparatus describedherein are those which represent an improvement in the art. Theindividual physical components of the apparatus used in the process ofthe invention, such as pipes, wires, switches, power supplies, pursers,sensors and computers, are currently in existence or can be manufacturedby the ordinary skilled artisan using available components. It is thespecific way in which these existing components are organized into theapparatus of the invention, and the actual process method formicroorganism reduction, that represent the improvement to prior art.

Process Method and Apparatus

[0017] The process method provides for a flow of medium/product to enterand exit a treatment space whereby, while in the treatment space, energyis pulsed into the treatment space via DC electric pulses at a definedvoltage, pulse frequency and pulse waveform, which is capable ofdisrupting the control mechanisms of target organisms. Preferably theflow of medium/product into the treatment space, and its treatmentthereof, is a continuous process. Many commercial processes require acontinuous flow operation, such as the production process for making afresh citrus juice. The process and apparatus of this invention areideally suited for such processes, because the invention may beinstalled in the continuous flow operation, be used to effectivelyreduce the naturally occurring microorganisms in the juice, withouthindering the speed or arrangement of the normal flow operation.Alternatively, the process is suitable for treatment of microorganismsin a non-continuous flow operation, such as the treatment of medium in acontainer. For example, control of microorganisms in a batch storagetank is often a problem. The medium contained in the batch storage tanksuch as juice in a large storage tank or liquids stored at the base of acooling tower may be circulated through the apparatus of this inventionand the microbial content may be reduced using the process of thisinvention.

[0018] The treatment space may be an area of any shape and size which issuitable for holding a conductive medium and subjecting it to low pulsedenergy. Preferably the treatment space is defined by the walls of achamber, the chamber being a partially enclosed space having an inletand an outlet which are connected to conduits for passing the mediumthrough the chamber for treatment. Within the chamber are at least onepair of electrodes for generating the low pulsed energy. Alternatively,the treatment space may be an area within a conduit itself, such thatthe treatment space is not enclosed except as defined by the conduitwall and is open to flow of the medium therethrough. The pair ofelectrodes are inserted through the conduit wall for generating the lowpulsed energy within the conduit.

[0019] The pair of electrodes are connected by electrical cables to apulse modulation unit, also referred to herein as a pulser unit orpulser. The pulse modulation unit contains the electrical components,i.e. capacitors, waveform generators, AC to DC transformers, etc., forgenerating the low voltage electrical pulses, by applying a defined DCvoltage to the pair of electrodes, and generating a defined pulsewaveform at a defined pulse frequency. Pulse modulation units arecommercially available. Preferably the pulse modulation unit is notlimited in operation to a single defined voltage, frequency and waveformbut is capable of adjustment of these parameters as necessary or desiredby the operator. The pulse modulation unit may be proximate or remotefrom the pair of electrodes. The pulse modulation unit is connected byelectrical cables to an AC electrical energy source.

[0020] As each family of organisms is different, the metaboliccomponents of the organism, and the information communicated within theorganism such as in the form of coded electrical pulses, are alsodifferent. Therefore, the process control settings of the invention arerequired to be variable so as to provide treatment to different organismtypes within various medium/product.

[0021] The process is controlled by a central processing unit (CPU),which may either be a component of the pulse modulation unit or beseparate therefrom. The CPU will be programmed to set operating limitsfor all control parameters. The principle control parameters are pulsefrequency, pulse waveform (pulse shape and amplitude) and level ofapplied voltage.

[0022] The pulse frequency may range from 1 to 1000 pulses per second,preferably 60 to 180 pulses per second, more preferably about 120 pulsesper second (i.e. 120 Hz).

[0023] The pulse waveform is defined by the pulse shape and pulseamplitude. The pulse shape may be any shape, e.g. monopulse, bipulse,bipolar, sine wave, spike, square, etc. Preferably the pulse shape is amonopulse in the positive domain. The pulse amplitude may be in therange of 6,000 V to 15,000 V, more preferably about 12,000 V.

[0024] The applied voltage is not limited but may be any suitablevoltage which is capable of generating a low voltage pulsed electricalenergy into the medium capable of reducing the microorganisms therein,without the formation of free radicals in the medium, without creationof osmotic shock in the medium, and without the generation of ionizingradiation such as lethal UV radiation in the medium.

[0025] The amount of applied energy is more critical to the inventionthan the applied voltage. The applied energy essentially means theamount of energy reaching the target organism in the medium. The appliedenergy varies based upon the conductivity or resistance of the medium.Thus, a medium having a higher resistance will require a higher voltagein order to generate the same level of applied energy. Furthermore,different organisms are sensitive to different levels of applied energy.Hence a target microorganism must be tested in the medium in which itwill be treated to determine the optimum voltage (as well as the optimumfrequency and waveform characteristics), and thus the optimum level ofapplied energy, to kill the organism. For most food and beverageapplications, the amount of applied energy must be less than or up to 1joule/ml. For blood the applied energy would be as minimal as possibleto kill the target organisms. The limits of applied energy may beobtained by optimizing the control parameters. For water and otherapplications, the amount of applied energy is not so limited, but maydesirably be so limited if effective against the organism to be killed.

[0026] The amount of applied energy is affected by the flow rate ofmedium/product through the treatment chamber. The flow rate may be inthe range of 1 to 300 gallons per minute, preferably in the range of 15to 25 gallons per minute, more preferably about 20 gallons per minute.For blood treatment the flow rate may be much less than 1 gallon perminute, when the invention is used in similar fashion to a dialysis, orat higher rates when treating large volumes such as those at bloodbanks.

[0027] As noted above, the key aspects of the pulsed electric energywhich result in mortality of the microorganism are the applied voltage,frequency and pulse waveform, which subject the target microorganism toa lethal applied energy. Since these key aspects are a function of themedium in which the target organism is contained, it is preferable tomonitor and control additional control parameters. Preferably theprocess and apparatus of the invention monitors and controls thefollowing parameters: 1) flow rate—is related to the number of pulsesrequired to kill an organism type and determines the number of reactionchambers in series required to kill the target organism; 2)conductivity—relates to the ease of pulse travel through the medium; 3)pH—assists in verification the medium has not changed characteristics;4) pressure—is monitored for verification of consistency in flow rate ofmedium thereby helping to ensure consistent delivery of uniform energyper unit volume of product; 5) temperature—is monitored to ensure theapplied energy has remained within design limits without raising thetemperature of the medium; 6) voltage—the AC power supply is monitored,and DC voltage is monitored across the electrical pulse delivery systemfor verification of consistent energy delivery; 7) current—is monitoredalong with voltage monitoring of the electrical pulse power supply toensure consistent energy feed conditions for consistent treatmenteffects; 8) electrical pulse frequency—is monitored to determineconsistent energy per unit volume of medium/product is obtained; 9)pulse shape—is monitored across the electrical pulse delivery unit toensure consistent treatment.

Process Control

[0028] The control of the process is such that high quality treatedmedium/product is tantamount. To accomplish this the process monitoringis also control based and interactive. The control system isdesigned/programmed for application specific environments. That is, eachtarget organism as well as medium/product characteristic is examined todetermine the appropriate level of applied energy, frequency and pulseshape necessary to achieve the desired level of microbial reduction inthe medium.

[0029] It is contemplated that each application may be different and itis anticipated several iterations may be required in pilot studies torefine the final operating conditions. This process allows thatflexibility with respect to control range settings of each processvariable that is being monitored.

[0030] An examination of application installation/location will allowfor a determination for the need for redundant or parallel installationsof the process. The target organism and medium/product characteristicsdetermine the number of treatment spaces or chambers to be placed inseries so as to deliver the correct energy, pulse frequency and pulseshape per unit volume.

[0031] The disruption of the metabolic/respiration cycle of the targetorganism in a specific medium is viewed as a solution couple and must beviewed together. This is a key concept of the invention which is notrecognized in the prior art. The amount of applied energy which iseffective to achieve mortality of the target microorganism must bedetermined by measuring the applied energy which achieves mortality forthe particular target organism(s) in the particular medium to betreated. Upon determination of optimum control variable ranges, theprocess control settings are programmed into the CPU.

[0032] The control system's programmable logic controllers are capableof storing operating data. The control system is equipped with aninteractive communication modem which allows data stored within to beaccessed from a remote location via telephone, cable or satellite links.This will also allow for system diagnostics to be performed from remotelocations.

[0033] All control variable sensors monitoring flow rate, conductivity,pH, pressure and temperature are preferably on both inlet and outletlocations of the reactor chamber. Voltage, current, frequency of pulseand pulse shape are preferably monitored on the appropriate energysystem; voltage and current on the AC and DC systems; frequency of pulseacross the pulse delivery system and shape of the pulse off the pulsedischarge system.

[0034] The PLC units for each sensed/monitored control variable are setto control ranges for each variable.

[0035] As one of the process objectives is to create a consistentmedium/product, at any time any control variable exceeds a preset limit(e.g. high and low settings for flow rate, conductivity, pH, pressure,temperature) an alarm function (e.g. audible, visual and/or electronic)will activate. At any time current voltage, frequency of pulse, orpulses shape does not meet preset values the same alarm functionactivates. Alarm activation will result in closing of downstreammedium/product conveyance system, opening of a downstream diversion pathto a designated storage system for later return back to treatmentsystem; recording of all alarm events; shut down and isolation ofmedium/product delivery system; perform diagnostics and await operatorinstructions; auto-dial operator via communication system interface inthe event operator is off-site. In the application of blood treatmentwhere blood is shunted from the patient through the treatment space andreturned to the patient, any parameter out of scale would shut thetreatment space off but allow the blood to continue flowing. The alarmfunction would alert the attendant of a malfunction.

Process Flow Schematic

[0036]FIG. 1 shows a process flow schematic which illustrates thesequence of process events in a preferred embodiment of the invention.As each application is most likely different, the medium/product andtarget organism couple will dictate the number of electric pulsetreatment spaces to be placed in series. Applied energy characteristicsin terms of voltage, frequency and pulse shape are generally less thanor up to one joule/ml for most food and beverage applications to preventstructural changes to the medium/product. Other applications may not beso limited.

[0037] The process is adaptive in that a series of electric pulsereactors may be sequenced to achieve microbial reduction withoutincreasing the applied energy per unit volume per pulse.

[0038] The process flow path allows for diversion in the event themedium/product does not receive optimum energy application and providesa method of medium/product recovery and retreatment. In-line bloodtreatment would not allow for diversion of blood. In the event ofmalfunction, the unit would shut off and alert the attendant.

Process Operation

[0039] The process operation is based on a controlled sequence ofevents. Normal operation passes medium/product through the pretreatmentsystem required by the application; e.g., citrus juice processing wouldbe preceded by culling, grading, disinfection of peel and extraction.The extracted juice would then be pumped through a series of treatmentspaces or chambers. If the processing line were large enough or operatedcontinuously, parallel process lines would be used to allow formaintenance and repairs.

[0040] The control panel modem interface allows for remote monitoringand control.

[0041] On normal operation the applied energy reduces the targetorganism in the treatment space or chamber and the medium/product ispumped to storage for packaging, etc. If the system senses a fault, theelectric valve to the treated medium/product storage tank closes and theelectric divert valve to the untreated divert storage tank opens. Afterrepairs, the untreated medium/product is pumped back to the treatmentspace or chamber.

[0042] Parallel operations in multiple production lines allows forcontinuous maintenance. Parallel production lines can be connected via acommon feed header and isolated by electric valves so individualtreatment spaces or chambers can be turned on and off via the CPU byestablishing a sequencing routine within the control system.

Applications

[0043] The process described herein is one of microbial reduction oforganisms within a conductive medium. The electric pulse process of theinvention may be applied to any conductive fluid, conductive solid orsuspended solid in a liquid or gas, preferably to pumpable foods andbeverages. Other applications of the electric pulse process include forthe reduction of micro-organisms in surface waters; for reduction ofmarine estuary facultative organisms for the purpose of environmentalodor control; for reduction of micro-organisms in power plant coolingtowers; for the microbiological reduction of volatile solids fromwastewater facilities; for reduction of microorganisms in conductivesolids such as in powderized materials; and for reduction ofmicroorganisms in a suspended solid such as in solids suspended in aliquid or gas to include air.

BRIEF DESCRIPTION OF THE FIGURES

[0044]FIG. 1 shows a process flow schematic which is intended toillustrate the process and apparatus of the invention for reduction ofmicroorganisms in a pumpable food using a continuous-flow treatmentsystem.

[0045]FIG. 2 shows a block diagram of a citrus juice processing systemincluding the apparatus of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0046] A. Development of Pilot Study Program for Treatment of Juices

[0047] 1. Project Objective

[0048] A pilot study was conducted to develop an effective non-thermaltreatment system for juices. At the outset, it was necessary to fullyestablish the objectives of the project all the way through full scalecommercialization. Therefore, discussions were held with many experts inthe citrus industry and scientific community as well as regulatoryagencies, marketing groups and food companies.

[0049] Based on many factors from varying points of view, aproject/product objective was developed. The project would utilizeexisting components to generate electric pulses to treat juices withoutaltering any of the characteristics associated with those of freshsqueezed juice. Additionally, it was decided orange and grapefruitjuices were the first two juices to be produced. After testing, andregulatory acknowledgment, other juices would then be produced.

[0050] In order for the application of the electric pulse process to becommercially viable, it was decided that it must be more economical thanthermal processes such as pasteurization and, from a consumer's point ofview, provide a more nutritious food product. Additionally, thetreatment technology itself must be accepted by the consumer. Further,the technology must be adaptable to meet performance standards such asthose proposed by the juice warning label rule and possibly others inthe future.

[0051] With the above in mind, a pilot testing program was initiated.All laboratory data used for certifications and validations wasperformed by qualified, certified and independent labs to includesampling.

[0052] 2. Initial Testing to Establish Baseline Data

[0053] The first element of the pilot study consisted of determiningwhich type of pulser and treatment space or chamber would optimize thereduction of micro-organisms without affecting the juice. Severaldifferent types of electric pulse modulation units and treatmentchambers were and are today available commercially. Treatment chamberscan produce electronic fields (E-fields) or they can produce electricpulses (submerged arc). A low energy electric pulser was selected. Thepulser equipment was Model #PPS22 manufactured by ScientificUtilization, Inc., Huntsville, Ala. The pulser included pulse modulationequipment. Pulsers may be equipped with pulse modulation equipment ormay be modified to include pulse modulation features by the artisanusing known technology. Pulse modulation equipment can provide manydifferent pulse shapes and pulse frequencies.

[0054] The purpose of the initial pilot tests was to establish baselinedata with which modifications to the technology/configurations could beaccomplished.

[0055] The pulser selected provided multiple pulse wave forms and wascapable of generating different pulse frequencies. The pulser selectedwas chosen because of its low energy density. The treatment chamberselected had a three-inch diameter inlet and outlet and thus providedadequate flow capacity.

[0056] Testing of the electric pulse system was conducted. Atrailer-mounted system was located at a production facility in Floridaand a side stream was created off the production line of this processingfacility to begin testing fresh squeezed, non-pasteurized juice.

[0057] The initial tests were conducted with a single treatment chamber.A battery of laboratory tests were performed. The single chamber systemwas tested at 20 gallons per minute and at two different pulsefrequencies. After review of the data it was concluded the electricpulse system was capable of reducing the background micro-flora of freshjuice.

[0058] It was concluded by review of the plate count data, it would bepossible to increase the microbial reductions by placing two treatmentchambers in series.

[0059] The initial tests on the electric pulse system looked promising.It was then decided the project warranted going to the next level.

[0060] The initial pilot test established baseline data. Heterotrophicplate count reductions and mold and yeast reductions were adequate.

[0061] Review of the metals data revealed the electrodes delivering theelectric pulses were not migrating into the juice. There was nomeasurable increase in temperature, no pH change and no change inappearance of the juice.

[0062] 3. Optimization of Technology for Treatment of Juices.

[0063] Two new 316L food grade stainless steel treatment chambers werebuilt and placed in series. The chambers were constructed from anexpanded pipe section, which involved dividing in half lengthwise a onefoot section of 3 inch diameter stainless steel pipe, and joining upperand lower stainless steel expansion plates about one foot in length andabout 7 inches in width to the respective pipe halves. End plates werethen constructed and joined to each end of the expanded pipe section tocreate a chamber. Each end plate had a central opening for connection to3 inch diameter inlet and outlet conduits. The construction using 3 inchconduit was sufficient to pass medium at a flow rate of 20 gpm. Whenconstructed, the treatment chambers resembled automobile mufflers andwere installed vertically to allow for draining. Two pairs of opposedcathode and anode electrodes insulated with one inch teflon insulatorswere installed through the end plates such that they were parallel tothe inlet and outlet conduits, treatment chamber and flow path of themedium therethrough. The tips of the opposed cathode and anodeelectrodes were spaced about ¼ inch apart.

[0064] To best optimize the technology for treatment of juice, thesystem was installed in the production facility and evaluated as anintegral part of the juice processing facility to determine not just itstechnical efficacy but to also to determine its practicality as atreatment component within a production facility.

[0065] While the new 316L food grade stainless steel chambers were beingconstructed, a complete review of the production facility was performedto determine the best installation location. It was determined the pulsemodulation unit could be installed adjacent to other main electriccomponents and the treatment chambers would be installed in the plantpiping system so as to properly isolate the electric pulse process fromthe rest of the facility. The location chosen provided washing, grading,extraction, chilling, storage, bottling and a clean in-placedisinfection system. A pulse frequency of 120 pulses per second wasselected as being preferred based upon the pilot study tests.

[0066] 4. Final Configuration of Technology.

[0067] A block diagram of the final citrus juice process showing thelocation of the electric pulse process is shown in FIG. 2. The two 316Lfood grade stainless steel treatment chambers were mounted vertically inseries.

[0068] The complete juice processing description is now described.

[0069] 1. Off-loading of fruit

[0070] 2. Pre-selection and culling to remove broken or damaged fruit

[0071] 3. Disinfection of whole fruit exterior using approved food gradecleaning solutions

[0072] 4. Washing of fruit using clean water

[0073] 5. Extraction of juice

[0074] 6. Chilling of juice

[0075] 7. Application of electric pulses

[0076] 8. Bottling of juice.

[0077] 9. Storage of bottled juice

[0078] It is further noted, as was determined during full scale testing,the use of the electric pulse process developed by the inventor as atreatment process for juices must be in conjunction with goodmanufacturing practices.

[0079] B. Full Scale Testing Program for Treatment of Juices

[0080] 1. Testing Objectives

[0081] The pilot studies verified the electric pulse process of theinvention was capable of meeting the product objective by reducingbackground micro-flora which resulted in a longer life product withoutaltering its fresh juice characteristics. The process of the inventionwas next tested under actual operational conditions to evaluate thepracticality of the process and study the treated juice product over along period of time.

[0082] Additionally, it is noted that treated samples were analyzed byvarious groups within the citrus processing and marketing areas toevaluate the product as being viable to the consumers.

[0083] Several studies were planned to evaluate the treated juiceproducts. Full scale exercises were necessary to determine the stabilityof the product over the period of time necessary to harvest, extract,pulse, bottle, and test. To evaluate the new 316L stainless steelchambers, metals were analyzed over time.

[0084] During the full scale testing phase, the treated juices weretasted by industry representatives for personal validation of theelectric pulse process of the invention, and all materials ofconstruction were examined to verify no food additives were beingintroduced into the juice.

[0085] The pulse modulation unit used (Model #PPS22) was a stand aloneNational Electric Code (N.E.C.) approved unit which was not located in awetted environment. No pumpable food or juice product was capable ofcoming in process contact with this unit. The treatment chamber was theonly portion of the electric pulse process which came in contact withthe product to be treated. Therefore, the treatment chamber wasevaluated.

[0086] During this phase of the project, it was concluded that allsampling for laboratory evaluation was to be done in sets of three. Thiswas done to validate the data and also serve to verify laboratoryprocedures. Final validation of data for regulatory and industry reviewwas accomplished in sets of seven.

[0087] 2. Treatment Chamber Analysis

[0088] One of the main objectives in evaluating the electric pulseprocess was to determine if its application on juices was capable ofcreating a food additive which would exceed 0.5 ppb, which is TheThreshold of Regulation by FDA. Another objective, equally as important,was to determine if its application on juices was capable of producing aproduct that would be safe and nutritious for the consumer.

[0089] The 316L stainless steel chambers were installed in the fullproduction facility in an isolated production line. A series of initialtests were performed to test the chambers. Microbiological testing,juice characteristics and metals were analyzed. Adequate microbiologicalreductions were shown to have occurred, the juice characteristics werefound not altered, and the metal analysis of the untreated and treatedsamples were found to be the same.

[0090] To further evaluate the treatment chambers, all materials ofconstruction were examined. The wetted parts of the electric pulsetreatment chambers are listed below with the materials of construction.Wetted Parts List Capable of Food Contact Item Material ofConstruction 1. Treatment chamber body 316L SS with passavated welds 2.Connecting piping and 316L SS flanges 3. Tubing Tygon-Food grade 4.Electrode holder Teflon-Food grade 5. Pressure gauges 316 SS Food Grade6. Electrodes: Cathode Anode 316 SS 25% copper 16-18% Cr 75% tungsten10-14% Ni 0.08% C 2% Mn 0.075% Si 0.30% S  2-3% Mo 0.1% N

[0091] The review of wetted materials revealed all components wereappropriate for food grade applications. The system was then tested todetermine whether a migration of cathode and anode materials might haveoccurred. Metals analyses were performed which included the Primary andSecondary Standards for Metals in Drinking Water (as no metals standardfor juice exists) and added to that list were any constituents whichwere in the materials of construction of the cathode and anode. Severaltests were performed. It is specifically noted citrus juices naturallycontain amounts of metals and minerals. The untreated samples varied inconcentration for several constituents. The treated samples varied inconcentration between the same values as the untreated samples.Therefore, it was concluded no migration of electrode materials hadoccurred.

[0092] Prior literature review had indicated in earlier years thatelectro-technology had difficulty in treating pumpable foods because ofelectrode erosion, free radicals and thermal heating.

[0093] None of these unacceptable elements had been detected in the fullscale testing data. An examination of prior work in this field revealedprevious pulsers used a great deal more energy, 150 joules/ml, to affectmicro-organisms. Because of such great energy required, materials usedin construction of the system were capable of migration. Additionally,large pulsers create heat as a result of the amount of energy applied.Large pulsers also have sufficient field strength to accelerateelectrons to very high kinetic energy states. The high field strengthsare required to cause electroporation of the cellular membrane ofmicro-organisms. Electroporation is one of the processes identified inthe earlier literature review to cause microbial dysfunctionality inpulsed electro-technology.

[0094] The pulser used in this study was considerably smaller in itsenergy delivery than prior art pulsers. The data observed in pilotstudies and initial chamber testing revealed that significant reductionsin microorganisms did occur and at acceptable levels. The reductions inbackground microflora which included naturally occurring spoilageorganisms stabilized the juice to acceptable levels.

[0095] The lower energy delivered to the juices was not creatingadditives. Additional literature review continued. Research chemists andmicrobiologists were consulted. Additional testing of the electric pulseprocess developed by the inventor on juices continued. Sufficient testruns were completed, samples collected and stored to analyze the juiceover a two month period. Samples were opened and analyzed for acceptanceto industry juice standards during this time frame. The juices, bothgrapefruit and orange, of many varietals and blends were analyzed duringthis phase. All products exhibited acceptable taste and appearancecharacteristics during this 60 day time frame.

[0096] During this time frame, the chambers were continually monitoredfor electrode wear. No visible or perceivable changes were detected inthe electrodes.

[0097] It was concluded during this phase of work that the process ofthis invention was capable of lethal effects to micro-organisms.

[0098] To determine the potential for other effects to be generated withrespect to the treatment of juices with electric pulses, a calculationof the energy density applied per chamber was performed and is shownbelow. The general form of the energy density equation (energy per unitvolume) for a pulse treatment chamber is:${E\quad d} = \frac{P\quad R\quad F \times E\quad p}{f}$

[0099] where Ed is the pulse energy per unit volume (mj/ml), which isalso referred to herein as the applied energy, Ep is the total energyper pulse delivered to the chamber (joules), PRF is the pulse repetitionfrequency (Hz), and f is the fluid flow rate.

[0100] For this specific system, we used two ¼ joule pulsers in a singlechamber operating at 120 Hz and treating a fluid flow of 20 gpm. Theenergy density is found to be:${E\quad d} = \frac{120\quad {Hz} \times 2.0 \times 0.25j}{20\quad {gal}\text{/}\min \times 3.78\quad l\quad i\quad t\quad r\quad e\text{/}{gal}}$E  d  per  chamber = 47.6  m  j/mlE  d = 47.6  m  i  l  l  i  j  o  u  l  e  s  per  milliliter

[0101] The low energy density explains the lack of electrode migration,why no temperature changes occurred and why no measurable or perceptiblechanges to the juice occurred due to the presence of free radicals. Theenergy densities and voltage potential of the field are not sufficientto cause changes. Further, laboratory results revealed no changesoccurred in constituents analyzed in controls versus treated samples formetals and all juice related characteristics.

[0102] It was concluded during the treatment chamber evaluation, the useof two 316L stainless steel treatment chambers provided adequatereduction of background microflora to achieve the desired results in thejuice without creating additives or altering the juice products.

[0103] It was then time to perform a shelf life study and metalsanalysis to validate the preliminary full scale testing results.

[0104] 3. 28 Day Shelf-Life Study and Metal Analysis

[0105] A 28-day shelf life study and metals analysis was performed. Thepurpose of the study was to track untreated fresh juice control samplesfor 28 days and determine its rate of spoilage, and compare treatedsamples for spoilage time frames.

[0106] Additionally, samples were analyzed for fresh juicecharacteristics. Temperature, pH and flow rates were recorded andsufficient treated samples were collected to perform in-house analysisbeyond the 28-day validation tests. Also metals were analyzed tovalidate no migration of materials of construction had occurred.

[0107] All sampling was performed by independent laboratories. Airquality and sample containers were analyzed during the collection of allsamples.

[0108] The shelf life study revealed the control samples spoiled between21 and 28 days. The treated samples were evaluated by tracking standardplate counts (SPC). The SPC of the treated samples at day 28 was lessthan the original untreated plate count control on day one.Additionally, mold and yeast treated sample values were also less at day28 than untreated plate count controls on day one.

[0109] Stored treated samples were opened after 30, 60 and 90 days andwere still acceptable. It should be noted samples were stored inconventional consumer bottles at 45° F.

[0110] Also evaluated during the shelf-life study were E. coli, totaland fecal coliform, and Salmonella. A naturally existing organism in thebackground microflora of juice is Klebsiella. It gives a false fecalcoliform reading. Klebsiella appeared in all control samples through the28-day shelf-life study but did not appear in any of the treatedsamples. The electric pulse process also eliminated this organism.

[0111] The metals analysis revealed the control samples metalconstituent values varied slightly. The treated sample values varied inthe same fashion.

[0112] It was concluded the variations in metals concentrations were aresult of the variations in the actual juice, not as a result of anychanges created by the electric pulse process. This data was consistentwith previous data. This conclusion was also supported by subsequenttests.

[0113] After review of this data and discussion of the data with otherindustry experts, it was concluded the full scale testing phase met thetest objectives.

[0114] 4. Proposed FDA Juice Labeling Rules

[0115] During the development of the final testing program forvalidation and submittal to FDA, proposed Juice Warning Label Rules werepublished Apr. 24, 1998 (Volume 63, Number 79).

[0116] A review of the proposed rule indicated a five log reduction intarget pathogen organisms would be required to be validated in all juiceproducts labelled as “Fresh” or a warning label would be mandated forthe product. Additionally, the target organisms were identified in theproposed rule to be Listeria monocytogenes and E. coli 0157:H7. It wascontemplated to expand the final pathogen testing program to includethese organisms.

[0117] C. Final Testing Program for Treatment of Juices and Milk

[0118] 1. Testing Objectives

[0119] The final testing phase of the project was developed to 1)demonstrate conclusively the efficacy of the electric pulse process atproviding a five log reduction of target pathogenic organisms in juices;2) subject treated juices to an independent organo-leptic testing panelto verify no changes in the juice product could be perceived; and 3)perform final metals evaluation of treated vs. non-treated juices toverify no changes in metal concentrations were occurring as a result ofusing the electric pulse process.

[0120] Additionally, it was decided to perform pathogen reductiontesting of target organisms occurring in milk. The exercise wasperformed to verify the electric pulse process' ability for microbialreduction in low acid products.

[0121] Although the proposed juice label warning rule identifiedListeria and E. coli 0157:H7 as target pathogens, it was also felt theelectric pulse process needed to be tested over a wider range oforganism types.

[0122] This was believed necessary to demonstrate to industryrepresentatives the process is applicable to other pathogens. And, ascertifications are required, the inventor wanted additional reasonableassurance as to the efficacy of the electric pulse process prior tofinal certifications.

[0123] The following portions of this section will present the finaldata related to testing prior to preparation of submittals.

[0124] 2. Pathogen Testing

[0125] (1) Juice

[0126] A full scale pathogen testing program was designed to validatethe electric pulse process's ability to achieve a five log reduction inpathogenic organisms.

[0127] After discussions with microbiologists, it was concluded thesafest testing location would be at the laboratory under very controlledconditions. Demonstrating a five log reduction required spiking juicewith known concentrations of organisms to a 10 log concentration andmeasuring reductions.

[0128] A full scale 20 gpm, dual chamber system was taken to theindependent laboratory in Orlando, Fla. and readied for testing. Thelaboratory obtained the selected organisms. At this phase of validation,it had been agreed all tests would be conducted in sets of seven.Because of the volume of juice required to cover the list of organismsand the number of samples which physically had to be analyzed, it wasagreed final testing would occur in three separate sessions.

[0129] The production facility and the laboratory were located indifferent cities. Good coordination of juice extraction andcontainerization, transportation and refrigeration as well astechnicians, and laboratory personnel was essential.

[0130] At each testing session, the juice was extracted and refrigeratedas during all other phases of this project. The juice was thentransported via refrigerated truck to the laboratory. Juice wastransported in 47 gallon, lined and sealed containers. All work wasperformed in a certified laboratory and supervised by qualifiedindividuals.

[0131] The Bacteriological Analytical Manual was used for all laboratorywork. Disposal of all contaminated materials was performed by acertified hazardous waste disposal contractor.

[0132] All tests were conducted to simulate the same conditions as hadbeen used to analyze the electric pulse process in both the pilot scaleand full scale testing.

[0133] The target pathogens inoculated and tested in fresh citrus juicesare listed below.

Target Pathogens to be Tested in Citrus Juice Using Electric PulseProcess for Microbial Reduction

[0134] 1. Listeria monocytogenes

[0135] 2. Clostridium sporogenes

[0136] 3. Salmonella typhimurium

[0137] 4. Lactobacillus lactus

[0138] 5. Endotoxin

[0139] 6. E. coli 0157:H7

[0140] 7. Aspergillus niger

[0141] 8. Penicillium digitatum

[0142] All samples were treated at 20 gpm, using two 316L stainlesssteel electric pulse treatment chambers in vertical series at a pulserate of 120 Hz at ½ joule/ml per chamber. Juice was pumped from eachindividually inoculated 47 gallon barrel through the treatment chambersand samples were taken on the discharge line. This procedure wasperformed each time a new organism was tested for reductions using theelectric pulse process.

[0143] The reduction testing for validation on Listeria, Clostridium,Salmonella, Lactobacillus and Endotoxin was performed. A laboratoryvalidation report for these pathogenic organisms was prepared. Thesummary of log reductions for the data sets for these organisms isincluded herein below in part (3) of this Section titled “Summary of LogReductions for Target Pathogenic Organisms”. The additional pathogenicorganisms tested in juice were E. coli 0157:H7, Aspergillus niger andPenicillium digitatum. These organisms were tested for reductions usingthe electric pulse process. A laboratory validation report for theseorganisms was prepared. The summary of log reductions for the data setsfor these organisms is also included herein below in part (3) of thisSection.

[0144] It is specifically noted that E. coli 0157:H7 has been identifiedas a resistant organism to any disinfection method. As a result thisparticular pathogen was subjected to electric pulses with samples takenand then the treated juice was pulsed a second time. This was done todetermine if additional reductions could occur by treating juice usingfour chambers. The results of the tests demonstrated that pulsing thejuice a second time resulted in an additional log value reduction ofmicroorganisms.

[0145] All reductions in pathogens inoculated in juice and treated usingthe electric pulse process with two chambers in series resulted in afive log or greater reduction. Additionally, and considering the logspike concentration recovered, 10⁹ CFU/gal, in most cases, the actualorganism reductions were greatly in excess of 100,000-fold reductions.

[0146] (2) Milk Testing

[0147] The application of the electric pulse process of the invention tomilk is intended to show efficacy of the process for pathogenicreductions in a different pH food. Raw milk and its target pathogensrepresents a reasonable example of a different food type andmicro-organism problem. Streptococcus faecalis and Bacillus cereus weretested under the same electric pulse process conditions described aboveas juice. Raw milk was obtained, inoculated and tested in the samefashion as the juice. The test was performed and a report was prepared.

[0148] The summary of log reductions for pathogens tested in milk isshown in part (3) of this Section. From the data, it is concluded allpathogens tested were reduced by five log or greater. This furthervalidated the electric pulse process' ability to reduce target pathogensin a different pH food.

[0149] (3) Summary of Log Reductions for Target Pathogenic Organisms

[0150] The data collected for validation of the electric pulse processis extensive. All validation sampling was performed in sets of seven. Inreview of the data, the log reductions in target pathogens wereconsistent by organism. All organisms tested were reduced by at leastfive log, a very impressive reduction considering the starting organismconcentration levels which were tested in the samples.

[0151] As all log reductions for each organism set were the same, onlyone value is shown in the following summary tables. Summary of LogReductions for Target Pathogenic Organisms in Juice Organism LogReduction-Set Average 1. Listeria monocytogenes 7 log 2. Clostridiumsporogenes 8 log 3. Salmonella typhimurium 7 log 4. Lactobacillus lactus7 log 5. Endotoxin 5 log 6. E. coli 0157:H7 5 log 7. Aspergillus niger 7log 8. Penicillium digitatum 7 log

[0152] Summary of Log Reduction for Target Pathogenic Organisms in MilkOrganism Log Reduction-Set Average 9. Streptococcus faecalis 6 log 10.Bacillus cereus 7 log

[0153] The data summarized herein indicates the electric pulse processis capable of reducing a wide range of organisms in different types ofconductive media.

[0154] 3. Organo-Leptic Testing

[0155] Test samples were subjected to an organo-leptic evaluation by asensory panel, to demonstrate that no food additives were created oradded by the electric pulse process or its materials of construction,and to demonstrate that the treated juice could not be distinguishedfrom untreated fresh squeezed juice. A report of the organo-lepticevaluation was prepared.

[0156] The conclusion drawn by the sensory report is that there were nodistinguishable differences between the treated and untreated samples.The panel liked both the treated and untreated samples, and both samplesreceived high relative scores.

[0157] 4. Metals Testing

[0158] The final evaluation was a metals analysis. There are nopublished standards for juices. The constituent list chosen for finalanalysis for metals is the U.S. Public Health Standards for DrinkingWater plus the materials of construction for the electrodes notidentified in the USPHS. It was considered this list would berepresentative of all constituents which could be expected to change if,in fact, changes were to occur.

[0159] It has been mentioned above that there does not appear to besufficient energy present at application to change the energy states ofmolecules in solution. The process appears to only provide sufficientenergy at a specific pulse shape and pulse repetition rate to lethallyaffect the microorganisms without effecting the medium.

[0160] The examination of metals therefore, represented the lastexamination related to potential food additives.

[0161] The samples for analysis were collected in sets of seven forfinal validation. The samples were collected from the same extractionrun performed to supply juice for the pathogen testing described above.A metals analysis was prepared.

[0162] Review of the data reveals fresh squeezed untreated (raw) citrusjuices contain metals and minerals. Specifically, barium, copper, iron,manganese, nickel, sodium, tungsten, and zinc were identified in the rawjuice. The metals analysis revealed the untreated juice control samplesvaried between specific concentrations. The treated samples alsocontained the same concentrations of metals as the untreated samples,with the exception of two iron values, and varied in the same fashion asdid the untreated samples. A literature review was performed todetermine published ranges of these constituents in raw juice. Allconcentrations in the raw juice and treated samples were withinpublished ranges including iron. The iron values varied in every sample.Two iron values in the treated samples were 0.02 mg/l and 0.04 mg/lhigher than the control sample variations. However, it is believed theslightly higher iron values were as a result of the varyingconcentrations in the raw juice, as no iron components are part of thiselectric pulse process. A comparison of published ranges of constituentswere made to the data reported herein. Concentrations of copper, iron,manganese, sodium and molydbium identified in the control samples werewithin the ranges reported in published literature. No published valuesfor barium, nickel or tungsten were found by the inventor.

[0163] It was concluded the background control values were, in fact,elements of the juice. The reported values for the treated samplesvaried within the same values as the untreated juice. It was concluded,no changes in metal concentrations had occurred as a result of treatingthe juice with the electric pulse process of the invention.

[0164] The above described preferred embodiments illustrate theprinciples of the invention but are not intended to limit the scope ofthe invention. Variations to these embodiments will be apparent to thoseskilled in the art and may be made without departing from the scope ofthe following claims:

I claim:
 1. A process for reducing microorganisms in a conductivemedium, which comprises subjecting the medium containing microorganismsto low voltage pulsed electrical energy, the low voltage pulsedelectrical energy being generated by a pair of electrodes contacting themedium and having a defined voltage, the low voltage pulsed electricalenergy having a defined frequency and defined waveform, wherein thepulsed electrical energy forms no free radicals, creates no osmoticshock, and generates no ionizing radiation, wherein the pulsedelectrical energy causes no detrimental change to the conductive medium,and wherein the pulsed electrical energy reduces the microorganisms inthe medium, provided that the conductive medium is not a pumpable foodor beverage.
 2. The process according to claim 1, wherein the conductivemedium is blood.
 3. The process according to claim 1, wherein theconductive medium is a conductive solid.
 4. The process according toclaim 1, wherein the conductive medium is a liquid or gas containingcontaminated solids which are suspended or immersed in the liquid orgas.
 5. The process according to claim 1, wherein the frequency of thepulsed electrical energy is in a range of 1 to 1000 pulses per second.6. The process according to claim 1, wherein the frequency of the pulsedelectrical energy is about 120 per second.
 7. The process according toclaim 1, wherein the pulse waveform has a shape which is a monopulse inthe positive domain.
 8. The process according to claim 1, wherein thepulse waveform has an amplitude in a range of 6,000 V to 15,000 V. 9.The process according to claim 8, wherein the pulse amplitude is about12,000 V.
 10. The process according to claim 1, wherein themicroorganisms in the conductive medium are reduced by about 5 log ormore after treatment.
 11. The process according to claim 1, wherein themedium containing microorganisms is subjected to the electric energypulse while the medium is passed through a treatment space.
 12. Theprocess according to claim 11, wherein the medium is passed through thetreatment space at a flow rate of 1 to 300 gallons per minute.
 13. Theprocess according to claim 12, wherein the flow rate of medium is in arange of 15 to 25 gallons per minute.
 14. The process according to claim11, wherein the treatment space is equipped with one or more pairs ofelectrodes connected to one or more pulser units for generating anelectrical energy pulse.
 15. The process according to claim 11, whereinthe treatment space is equipped with two or more pairs of electrodesconnected to two or more pulser units for generating two or morerespective electrical energy pulses.
 16. The process according to claim15, wherein the two or more electric energy pulses generated by the twoor more pairs of electrodes connected to two or more respective pulserunits have a different pulse frequency, different pulse shape, and/ordifferent pulse amplitude, for the treatment of one, two or moredifferent types of microorganisms contained in the medium.
 17. Theprocess according to claim 15, wherein the two or more pulser unitssubject the microorganisms contained in the medium to different levelsof applied energy.
 18. The process according to claim 11, wherein themedium is passed through a plurality of two or more treatment spaces,each treatment space being equipped with at least one pair of electrodesconnected to at least one pulser unit for generating an electricalenergy pulse.
 19. The process according to claim 11, wherein thetreatment space is within a conduit.
 20. The process according to claim11, wherein the treatment space is within a chamber.
 21. The processaccording to claim 1, wherein the low voltage pulsed electrical energysubjects the microorganisms to an applied energy of less than or up to 1joule per milliliter.
 22. The process according to claim 1, wherein theflow rate is less than 1 gallon per minute.
 23. The process according toclaim 1, wherein the low voltage pulsed electrical energy subjects themicroorganisms to an applied energy of greater than 1 joule/ml.
 24. Aprocess for killing a specific target microorganism in a conductivemedium, which comprises (a) subjecting the medium containing thespecific target microorganism to an electric energy pulse having apredetermined pulse waveform and predetermined pulse frequency, therebysubjecting the microorganism to a predetermined applied energy, (b)measuring the effectiveness of the electrical energy pulse on killingthe microorganism, (c) adjusting one or more of the pulse waveform,pulse frequency, or applied energy of the electric energy pulse, (d)subjecting the medium containing the microorganism to the adjustedelectric energy pulse, (e) measuring the effectiveness of the adjustedelectric energy pulse on killing of the microorganism, and (f)optionally repeating steps (c), (d) and (e) to determine the optimumpulse waveform, pulse frequency and applied energy to kill themicroorganism provided that the conductive medium is not a pumpable foodor beverage.
 25. The process according to claim 24, wherein the mediumcontaining the microorganism is subjected to the electric energy pulseby passing the medium containing the microorganism through an energypulser treatment space at a predetermined flow rate.
 26. The processaccording to claim 25, wherein the flow rate of the medium containingthe microorganism is also adjusted to optimize killing themicroorganism.
 27. The process according to claim 24, wherein thespecific target microorganism is a member selected from the groupconsisting of Listeria, Clostridium, Salmonella, Lactobacillus,Endotoxin, E. coli, Aspergillus niger, Penicillium, Streptococcus,Bacillus and Klebsiella.
 28. An apparatus for the treatment of aconductive medium containing microorganisms, which comprises a firstconduit for passing the conductive medium therethrough, said firstconduit connected in flow path arrangement to a treatment space forpassing the conductive medium into the treatment space, the treatmentspace being equipped with an electric energy pulser for treating themicroorganisms with an applied energy, and a second conduit connected inflow path arrangement to the treatment space for passing the treatedmedium out of the treatment space, wherein the conductive medium is nota pumpable food or beverage.
 29. The apparatus according to claim 28,wherein the first conduit is equipped with at least one sensor formonitoring the pH, pressure, temperature, conductivity and/or flow rateof the conductive medium.
 30. The apparatus according to claim 28,wherein the second conduit is equipped with at least one sensor formonitoring the pH, pressure, temperature, conductivity and/or flow rateof the conductive medium.
 31. The apparatus according to claim 28,wherein the electric energy pulser is equipped with at least one sensorfor monitoring the current, voltage, pulse shape and/or pulse frequency.32. The apparatus according to claim 28, wherein the treatment space iswithin a conduit or chamber.
 33. The apparatus according to claim 28,which includes at least one control for adjusting the pulse frequency,pulse shape, pulse amplitude or pulse voltage.
 34. A conductive mediumwhich is treated by the process according to claim 1, provided that theconductive medium is not a pumpable food or beverage.
 35. The conductivemedium according to claim 34, which is blood, wastewater, a conductivesolid or a suspended solid.
 36. A conductive medium which is treated bythe process according to claim 24, provided that the conductive mediumis not a pumpable food or beverage.
 37. The conductive medium accordingto claim 36, which is blood, wastewater, a conductive solid or asuspended solid.
 38. A conductive medium which is treated with theapparatus according to claim 28, wherein the conductive medium is blood,wastewater, a conductive solid or a suspended solid.